Exhaust pipe silencer with side branch chambers and baffled elbow sections



July 5, 1966 E. G. STRAW 3,259,206

EXHAUST PIPE SILENCER WITH SIDE BRANCH CHAMBERS AND BAFFLED ELBOWSECTIONS Filed June 18, 1964 INVENTOR. fiJreZ 6'. .5'raw.

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United States Patent 3,259,206 EXHAUST PIPE SILENCER WITH SIDE BRANCHCHAMBERS AND BAFFLED ELBOW SECTIONS Eldred G. Straw, Grass Lake, Mich.,assignor to Walker Manufacturing Company, Racine, Wis., a corporation ofDelaware Filed June 18, 1964, Ser. No. 376,108 3 Claims. (Cl. 181-59)This invention relates generally to exhaust systems for internalcombustion engines, and more particularly, to an exhaust gas conduit foran automotive engine.

It is an object of the present invention to provide an exhaust gas pipeconstruction that is formed with a plurality of creases or indentationsto enhance the exhaust sound attenuating characteristics of the pipeconstruction.

It is another object of the present invention to provide an exhaust gaspipe construction having deviating and restricting means formed incertain bent sections thereof to increase the turbulence of the exhaustgases flowing through the pipe construction, thereby attenuating exhaustgas noise.

Other objects and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawing, wherein:

FIGURE 1 is a longitudinal cross-sectional view of an exhaust gas pipeconstruction embodying the present invention;

FIGURE 2 is an enlarged transverse cross-sectional view taken along theline 22 of FIGURE 1; and

FIGURE 3 is an enlarged bottom elevational view of the structureillustrated in FIGURE 1, taken in the direction of the arrow 3 thereof.

Referring now to FIGURE 1 of the drawing, an exhaust gas pipeconstruction is shown as comprising a hollow elongated tube or shell 12which is formed with a plurality of longitudinally spaced necked-downsections, generally designated 14. The opposite ends of the shell 12 arealso necked down into inlet and outlet sections or bushings 16 and 18,the former of which is adapted to be connected to a suitable conduit(not shown) communicating the pipe construction 10 with the exhaustmanifold of a conventional automotive engine (not shown).

The bushing sections 16 and 18, together with the plurality ofnecked-down sections 14, form a series of axially adjacent chambers,generally designated 20. As seen in FIGURE 1, a plurality of louveredcylindrical gas flow tubes 22, 24, 26 and 28 are disposed within four ofthe chambers 20 and are supported coaxially therewithin by beingspotwelded or similarly secured at least atone end to the innerperipheries of the necked-down sections 14 and/or the bushing sections16 and 18. The tubes and the bushings 16 and 18 are of substantially thesame inside diameters and this corresponds to the size of conventionalexhaust and tailpipes. Thus, the shell 12 is somewhat larger in diameterthan the diameter of the normal gas flow path through the pipeconstruction 10.

In general, the plurality of chambers 20 function to attenuate differentexhaust sound frequencies in a manner such that the entire frequencyrange or spectrum of undesirable exhaust sound is attenuated by the timethe exhaust gases reach the terminal end of the pipe construction 10.For example, the chambers 20 cincumjacent the tubes 22, 24 and 26 act asspit chambers to attenuate high frequencies and the tube 28 functionswith a nonperforate shell 30 to provide a tuned chamber to attenuatelower frequencies. Additional silencing sections may be provided asneeded.

3,259,206 Patented July 5, 1966 In order that the pipe construction 10conform with the shape or configuration of the frame and chassis of theautomotive vehicle with which it is to be operatively associated, it isnecessary that bends be formed in it at series of longitudinally spacedlocations, as seen at 32, 34 and 36 in FIGURE 1. These bends cannot bereadily formed in sections containing internal pipe sections (i.e.,silencing sections) but it has been found that sound attenuation can beobtained by bending the enlarged empty sections, such as 32, 34 and 36.Such bending is preferably done on a vertical bending machine whereby aplurality of creases or radially inwardly extend indentations are formedon the concave side of the shell 12 in each of the bend sections 32, 34and 36. In particular, the creases or indentations which are formed atthe sections 32, 34 and 36 are arranged in two groups or triads,generally designated 38, of three indentations each. As best seen inFIGURE 2, each of the triads 38 comprises three separate indentations38a, 38b and 38c, the former of which is slightly curved and extendstransversely of the shell 12, and the latter two of which are somewhatmore arcuate in shape than the indentation 38a and curve about theopposite ends thereof. It may be noted that the relative lengths anddepths of each of the indentations 38a, 38b and 38c comprising thetriads 38, will vary in accordance with the angle of bending or therelative angularity between the longitudinal axis of the shell 12 andthe axis of inclination of the bent portion of the shell 12, with boththe lengths and depths of the indentations increasing as the angle ofbending increases.

The indentations 38a, 38b and 380 comprising the groups or triads 38, incombination with the enlarged diameter of the gas passage through thebent sections 32, 34 or 36 as compared with the normal gas passagediameter of sections 16, 18, 22, 24, 26, or 28, have a desirable exhaustsound attenuating effect on exhaust gases as they are transmittedthrough the pipe construction 10. More specifically, the indentationshave a slight restrictive andbafiie eifect which changes the velocityand increases the turbulance of the exhaust gases as they pass througheach bend sections 32, 34 and 36 of the shell 12, thereby reducing thesound energy of the exhaust gases. Also the indentations 38a, 38b and380 comprising the triads 38 tend to make the bend sections 32, 34 and36 somewhat more rigid and thereby reduced pipe noise. I

While it will be apparent that the herein illustrated embodiment of theexhaust pipe construction 10 of the present invention is well calculatedto fulfill the objects above stated, it will be appreciated that thisconstruction is suspectible to modification, variation and changewithout departing from the proper scope or fair meaning of the subjoinedclaims.

What is claimed is:

1. In' an exhaust gas pipe for transmitting exhaust gases from anautomotive engine,

a hollow elongated shell,

said shell having a plurality of longitudinally spaced necked-downsections defining a series of chambers,

said tube having at least one bent section providing a chamber,

a triad of arcuately configured and inwardly extending projectionsformed onthe concave of said bent section,

said triad comprising one projections that extends transversely of saidshell and a pair of projections which extend arcuately about theopposite ends of said transversely extending projection,

said projections being adapted to restrict the flow of exhaust gasesbeingtransmitted through said chamber and thereby increase theturbulan-ce of said exhaust gases to remove exhaust sound energy fromsaid gases and improve the sound attenuating properties of said exhaustpipe.

2. In an exhaust conduit for conducting exhaust gases from an automotiveengine, a hollow tube providing a passage for exhaust gas, said tubehaving a bent section providing a gas passage section that is notstraight, said bent section having a concave side and a convex side, theconcave side of said tube bent section having a triad of inwardlyextending projections one of which extends crosswise of the tube and apair of which extend lengthwise of the tube and are located respectivelyat opposite ends of said crosswise projection, said projections beingadapted to restrict the flow of exhaust gases through the tube andincrease the turbulence of the gases to remove sound energy from thegases and improve the sound attention of the tube. I

3. A conduit as set forth in claim 2 wherein said bent section extendsthrough an arc and has two of said triads formed therein, one of saidtriads being located adjacent each end of said arc.

References Cited by the Examiner UNITED STATES PATENTS 11/1896 Eichhorm.

11/1938 Rauen 181-59 2/1939 Deremer 181-35 5/1939 Peuthert 287-179 X4/1951 Gaugler 181-36 10/1957 Wilman 181-36 7/1962 Gerli 138-37 X 3/1963Lesser 285-179 X 9/1963 LudloW et al. 181-48 5/1964 Sailler 181-62 XFOREIGN PATENTS 8/1951 France. 1/ 1957 Switzerland.

OTHER REFERENCES Hettich, 340,799 (A.P.O.), May 1943.

LOUIS I. CAPOZI, Primary Examiner.

LEO SMILOW, GERALD F. BAKER, Examiners.

R. S. WARD, Assistant Examiner.

2. IN AN EXHAUST CONDUIT FOR CONDUCTING EXHAUST GASES FROM AN AUTOMOTIVEENGINE, A HOLLOW TUBE PROVIDING A PASSAGE FOR EXHAUST GAS, SAID TUBEHAVING A BENT SECTION PROVIDING A GAS PASSAGE SECTION THAT IS NOTSTRAIGHT, SAID BENT SECTION HAVING A CONCAVE SIDE AND A CONVEX SIDE, THECONCAVE SIDE OF SAID TUBE BENT SECTION HAVING A TRIAD OF INWARDLYEXTENDING PROJECTIONS ONE OF WHICH EXTENDS CROSSWISE OF THE TUBE AND APAIR OF WHICH EXTEND LENGTHWISE OF THE TUBE AND ARE LOCATED RESPECTIVELYAT OPPOSITE ENDS OF SAID CROSSWISE PROJECTION, SAID PROJECTIONS BEINGADAPTED TO RESTRICT THE FLOW OF EXHAUST GASES THROUGH THE TUBE ANDINCREASE THE TURBULENCE OF THE GASES TO REMOVE SOUND ENERGY FROM THEGASES AND IMPROVE THE SOUND ATTENTION OF THE TUBE.